1. Field of the Invention
This invention relates to a far infrared ray emitting, odor-absorbing material which is made of cellulose fiber, especially of cellulose acetate fiber, and an inorganic core material having adhered thereto an ultrafine powder of alumina hydrate or silica hydrate which is chemically produced in an aqueous dispersion of said inorganic core material.
2. Description of the Background
Fiber products including textiles, lace, knits, nonwoven fabrics, felts, etc. are used mostly as clothing materials. Fibers are spun into strands or yarns by spinning processes, and are woven into textiles, knitted into knitting goods, packed and adhered into nonwoven fabrics, or otherwise processed to produce other fiber products.
Fibers from which textiles or yarns are prepared are called spinning and weaving fibers. Among the spinning and weaving fibers, those prepared into the clothing materials are called clothing fibers. Spinning and weaving fibers are broadly classified into naturals fibers, such as the fibers of vegetable, animal, or mineral origin, and synthetic fibers.
Synthetic fibers are grouped into inorganic fibers, (e.g. glass or ceramic fibers), those in the rayon family, and the synthetic fibers produced from substances derived from petroleum (e.g. nylon, polyester, acrylic fibers, etc.).
Fibers of the rayon family are of two types. One is those made from regenerated cellulose (wood pulp). Viscose and cuprammonium belong to this group. Both are derived from wood pulp dissolved in caustic soda. The other type is cellulose acetate fibers which are the reaction products (esters) of acetic acid and cellulose. Depending on the degree of acetylation cellulose acetate fibers are grouped into diacetate (usually called simply "acetate") and triacetate.
Triacetyl cellulose is produced by the reaction of acetic anhydride and cellulose. All three hydroxyl groups in glucose recurring units in cellulose are esterified by acetic acid in triacetyl cellulose. Triacetate is produced by dissolving the triacetyl cellulose into a suitable solvent, typically into a mixed solvent of methylene chloride and methanol, and by forcing the solution through spinnerets. Diacetyl cellulose is produced by adding water to triacetyl cellulose and heating the mixture to hydrolyze. The product is dissolved into acetone and the solution is spun to produce diacetate (or acetate). Acetate fabrics are known for their brilliance of color and ability to drape well, properties that have made them particularly successful as apparel fabrics. Triacetate yarns have many of the same properties as diacetate but are particularly known for their ability to provide pleat retention in apparel. Short fibers (staples) of cellulose acetate are used as filling materials in pillows, mattress pads, and quilts and also as filtering agent of cigarettes. They are very frequently used blended with other fibers.
In contrast to natural fibers and synthetic fibers having round, circular cross sections, the cross sections of acetate and triacetate fibers are concaved circles like leaves of clover. This makes the specific surface area of cellulose acetate fibers large.
Despite the above characteristics, cellulose acetate fibers do not possess a far infrared ray emitting, heat-retaining property or a deodorizing effect which are demanded of fibers used for sanitary, health-care, or medical purposes.
The present inventors had previously developed a far infrared ray emitting body comprising a base material or an inorganic core material having an ultrafine inorganic powder with a closely distributed particle size adhered on said base or core material, and filed an application for patent (U.S. application Ser. No. 07/296,026now U.S. Pat. No. 4,886,972). Specifically, the invention comprised a core material having adhered thereto an ultrafine powder of a particle size below 500 angstrom of one or more compounds selected from the group consisting of alumina hydrate, silica hydrate, and the mixture thereof which is chemically produced in an aqueous dispersion of said core material.
The further studies by the inventors were directed to applications of the far infrared ray emitting body. As a result the inventors found that by the combination of the far infrared ray emitting body and cellulose acetate fibers provides the latter with a superior far infrared ray emitting, heat-retaining characteristics as well as a superb deodorizing effect. This finding has led to the completion of the present invention.